Parents Not Spoken In 2 Years

My parents have not spoken to me in 2 years and 1 month. I have tried to maintain communication with them, but they have ignored any attempts. They have been told over and over how much it would mean for them to be at my wedding, but still no response. I am now in a position of either walking myself down the aisle or asking my brother. But I feel as though this is putting him in an awkward position with my father. I just don`t know what to do since my fiance is insisting someone walk me down. Any suggestions?